Different motherboards have different beeping codes. When there is no memory, it beeps indicating a problem. When you install memory it stops beeping. It may be that your motherboard simply does not beep when everything is OK. See if you can boot or install OS. If you can, then most likely everything is fine and your motherboard simply runs this way.
Another thing that you can do is to try and run MemTest.
If you have problems doing above things, than it is indication of real problems.